![]() Infrared thermography, charge-coupled device-based thermoreflectance microscopy, and micro-Raman spectroscopy have been performed to extract the thermal resistance of the components. This paper describes a complete thermal characterization of AlGaN/gallium nitride (GaN) on silicon carbide high electron-mobility transistors (HEMTs) when devices are operating in dc bias, pulsed, and continuous wave. As a direct temperature measurement within a channel is most of the time not achievable, the common approach is to measure the device temperature at different locations close to the hotspot and then to use simulations to estimate the channel temperature. Thermal model development and suitable temperature measurement systems are necessary to quantify the channel temperature of devices in real operating conditions. Performance and reliability of wide bandgap high-power amplifiers are correlated with their thermal behavior. Results of failure analysis using various microscopy and spectroscopy techniques are presented and failure mechanisms observed at the high electric field values typical of the operation of these devices are reviewed. The present paper proposes a methodology for the analysis of failure modes and mechanisms of GaN HEMTs, based on (i) DC and RF stress tests accompanied by an (ii) extensive characterization of traps using deep level transient spectroscopy and pulsed measurements, (iii) detailed analysis of electrical characteristics, and (iv) comparison with two-dimensional device simulations. The role of temperature in promoting GaN HEMT failure is controversial, and the accelerating degradation factors are largely unknown. Despite the large efforts spent in the last few years, and the progress in mean time to failure values, reliability of GaN HEMTs, and millimeter microwave integrated circuits still represent a relevant issue for the market penetration of these devices. High Electron-Mobility Transistors (HEMTs), as resulting from a detailed accelerated testing campaign, based on reverse bias tests and DC accelerated life tests at various temperatures. In the present paper we review the most recent degradation modes and mechanisms recently observed in AlGaN/GaN (Aluminum Gallium Nitride/Gallium Nitride). This methodology is based on the continual monitoring of the RF waveforms and DC parameters under overdrive conditions in order to assess the degradation of the transistor characteristics in the RF power amplifier. Finally, an advanced time-domain methodology is presented in order to investigate the device’s reliability and to determine its safe operating area. ![]() Furthermore, a nonlinear electro-thermal AlGaN/GaN model with a new additive thermal-trap model including the dynamic behavior of these trap states and their associated temperature variations is presented, in order to correctly predict the RF performance during real RF operating conditions. A new trap investigation protocol to obtain a complete overview of trap behavior from DC to radio-frequency operation modes, based on combined pulsed I/V measurements, DC and RF drain current measurements, and low-frequency dispersion measurements, is proposed. Thus, the aim of this research is to investigate the trapping effects and the reliability aspects of the GH50 power transistors for C-band applications. But this technology still suffers from the trapping phenomena, principally due to lattice defects. A first demonstration of GaN-MMIC transmitter has been developed and put on board the PROBA-V mission. GaN-based high electron mobility transistors (HEMTs) are promising candidates for future microwave equipment, such as new solid state power amplifiers (SSPAs), thanks to their excellent performance. The operation with mismatched load shows a stronger degradation, with a positive threshold voltage shift and a drop in saturation drain current, due principally to the high temperature reached by the devices during RF stress. In particular, the operation with optimum PAE load impedance induces slight positive threshold voltage shift. The results show a drift of RF performances due to a variation of electrical parameters. The analysis is carried out with two different output load impedances: optimum of PAE and mismatched impedance. ![]() The reliability study is carried out in class AB operation, under RF operating excitation at high drain voltages and overdrive conditions (12 dB compression). The presented technique is based on the continued monitoring of the RF waveforms and DC parameters in order to assess the degradation of transistor characteristics in RF power amplifiers. This paper reports an advanced time-domain methodology to investigate the device reliability and determine its safe operating area of AlGaN/GaN HEMTs.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |